Impeller,  And Pump And Fluid Delivery Device Using The Impeller

ABSTRACT

An impeller, and a pump and a fluid delivery device using the pump are disclosed. An impeller includes an base plate and a plurality of long blades and a plurality of short blades disposed on the base plate. The impeller further includes a shaft mounting portion disposed on the base plate. The plurality of long blades and the plurality of short blades are alternatively arranged on the base plate and surround the shaft mounting portion. The long blades and the short blades are all arcuate blades. The above fluid delivery device, the pump and the impeller have improved efficiency.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201510882338.9 filed in The People's Republic of China on Dec. 3, 2015.

FIELD OF THE INVENTION

This invention relates to an impeller, and in particular, to a centrifugal impeller and a pump and a fluid delivery device using the impeller.

BACKGROUND OF THE INVENTION

A centrifugal pump usually includes a motor which drives an impeller to rotate. Prior to startup of the pump, a pump housing and a suction pipe are filled with liquid. When the impeller rotates at high speed, the impeller drives the liquid between blades to rotate therewith. Because of the centrifugal force, the liquid is thrown from a center of the impeller to an outer edge of the impeller, and its kinetic energy is increased accordingly. When the liquid enters a pump casing, because a flow passage in the volute pump casing expands progressively, the speed of the flow progressively decreases. As a result, part of the kinetic energy is converted into static pressure energy, such that the liquid is discharged from an outlet with high pressure. At the same time, because the liquid is thrown out, a vacuum is established at a central area of the impeller and, as a result, the pressure at the liquid level is greater than that at the central area of the impeller. Therefore, the liquid in the suction pipe enters the pump due to the pressure difference. As the impeller rotates continuously, the liquid is continuously sucked in and propelled out, thereby achieving the liquid delivery purpose.

The impeller of the conventional pump includes an base plate and straight blades disposed on the base plate. In order to make the flow of the fluid in the pump more stable, the blades are usually uniformly distributed on the impeller. However, such a centrifugal pump has poor liquid delivery efficiency.

SUMMARY OF THE INVENTION

Thus, there is a desire for an impeller with improved efficiency, and a pump and a fluid delivery device using the impeller.

An impeller includes an base plate, a plurality of long blades and a plurality of short blades disposed on the base plate. The impeller further includes a shaft mounting portion disposed on the base plate. The plurality of long blades and the plurality of short blades are alternatively arranged on the base plate and surround the shaft mounting portion. The long blades and the short blades are all arcuate blades.

Preferably, the shaft mounting portion is a circular cylinder protruding from the base plate.

Preferably, the long blade extend along radial directions of the base plate, each long blade has a terminating end adjacent to the radial rim of the base plate and a start end of each long blade relatively closed to the shaft mounting portion comparing to the terminating end of the long blade, a ratio of a distance between a start end of each long blade and an outer circumferential surface of the shaft mounting portion, to a diameter of the base plate is greater than or equal to 0.219, and less than or equal to 0.4;

and/or, a ratio of a distance between a start position of each of the short blades and the start position of one adjacent long blade, to the diameter of the base plate is greater than or equal to 0.219, and less than or equal to 0.4.

Preferably, the long blades are spaced from each other at uniform intervals, the short blades are spaced from each other at uniform intervals, and distances between a start end of each short blade and start ends of two long blades neighboring the short blade are the same;

Preferably, the base plate defines a plurality of balance holes in the base plate.

Preferably, the balance holes uniformly distributed on the base plate.

Preferably, centers of the balance holes are located on a same circle, and a ratio of a diameter of the circle to a diameter of the base plate is greater than or equal to 0.36, and less than or equal to 0.9;

and/or, a cross section area of each balance hole is greater than or equal to 9 mm², and less than or equal to 240 mm²;

and/or, each balance hole has at least one of the following shapes: round, square, triangle, and rectangle.

Preferably, the shaft mounting portion is connected to the base plate with a smooth transition therebetween.

A pump includes a driving mechanism and an impeller in accordance with any one as described above. The impeller is connected to the driving mechanism, and the driving mechanism is configured to drive the impeller to rotate.

Preferably, the pump further includes a pump housing, the pump housing includes a main body and a cover disposed on the main body, the main body includes a volute-shaped receiving portion and a flow guide portion (343) connected to the receiving portion, the driving mechanism is mounted to the cover, and the receiving portion defines a receiving chamber accommodating the impeller.

Preferably, the profile of the receiving chamber of the receiving portion is a spiral line substantially formed by a plurality of arc segments approximated, a ratio of a diameter D1 to a diameter D2 is greater than or equal to 1.05, and less than or equal to 1.1, wherein D1 is a diameter of one of the arc segments, at which the starting point of the spiral line is located, D2 is a diameter of the base plate;

and/or, a ratio of an outlet flow area of the receiving portion to an outlet flow area of the impeller is greater than or equal to 0.2, and less than or equal to 0.5;

and/or, a ratio of a distance between the impeller and a bottom wall of the receiving portion of the main body to the diameter of the base plate is greater than or equal to 0.04, and less than or equal to 0.12.

Preferably, the flow guide portion defines an outlet passage communicating with the receiving chamber of the receiving portion, and a diameter of the outlet passage increases progressively in a direction away from the receiving portion; and/or, the pump further includes an inlet pipe, the inlet pipe is disposed at one side of the receiving portion opposite from the cover, and an inner chamber of the inlet pipe is in communication with the receiving chamber of the receiving portion.

Preferably, the cover includes a mounting portion and a cover portion disposed on the mounting portion, the cover portion covers on the main body, and the driving mechanism is mounted in the mounting portion.

Preferably, the pump further comprises a mounting base , and the mounting portion of the cover is fixedly disposed on the mounting base.

Preferably, the mounting base includes a base body and a retaining portion disposed on the base body, the retaining portion includes two opposed claws, and the mounting portion is retained between the two claws.

Preferably, the driving mechanism is a single phase motor.

In the pump of the present invention, the impeller includes the alternatively arranged long and short arcuate blades, which further optimizes the design of the flow passage in the pump housing, thereby resulting in more smooth and stable flow of the fluid and enhanced fluid delivery efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pump according to one embodiment of the present invention.

FIG. 2 is a perspective, exploded view of the pump of FIG. 1.

FIG. 3 is a perspective, exploded view of the pump of FIG. 1, viewed from another aspect.

FIG. 4 is a sectional view of a pump housing of the pump of FIG. 1, taken along line IV-IV thereof

FIG. 5 is a perspective view of an impeller of the pump of FIG. 2.

FIG. 6 is a top plan view of the impeller of the pump of FIG. 5.

FIG. 7 is a cross sectional view of the pump of FIG. 1, taken along line VII-VII thereof.

Below, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The technical solutions of the embodiments of the present invention will be clearly and completely described as follows with reference to the accompanying drawings. Apparently, the embodiments as described below are merely part of, rather than all, embodiments of the present invention. Based on the embodiments of the present disclosure, any other embodiment obtained by a person skilled in the art without paying any creative effort shall fall within the protection scope of the present invention.

It is noted that, when a component is described to be “fixed” to another component, it can be directly fixed to the another component or there may be an intermediate component. When a component is described to be “connected” to another component, it can be directly connected to the another component or there may be an intermediate component. When a component is described to be “disposed” on another component, it can be directly disposed on the another component or there may be an intermediate component. The directional phraseologies such as “perpendicular” or similar expressions are for the purposes of illustration only.

Unless otherwise specified, all technical and scientific terms have the ordinary meaning as understood by people skilled in the art. The terms used in this disclosure are illustrative rather than limiting. The term “and/or” as used in this disclosure means that each and every combination of one or more associated items listed are included.

Referring to FIG. 1, a pump 100 in accordance with one embodiment of the present invention is used to draw a liquid such as water or oil so as to deliver the liquid from a container to another container or an outside environment, for example, drain water off a water pool. In this embodiment, the pump 100 is a centrifugal pump. It should be understood that the pump 100 may also be used to draw and/or drain a fluid such as gas.

Referring to FIG. 2 and FIG. 3, the pump 100 includes a mounting base 10, a pump housing 30, a driving mechanism 50, and an impeller 70. In the illustrated specific embodiment, the pump housing 30 is connected to the mounting base 10, and the driving mechanism 50 and the impeller 70 are received in the pump housing 30. The impeller 70 is disposed on the driving mechanism 50. The driving mechanism 50 is used to drive the impeller 70 to rotate to deliver the liquid from one side of the pump housing 30 to the other side of the pump housing 30, thus achieving the fluid delivery by the pump.

In this embodiment, the mounting base 10 is generally an irregular block-shaped base body for mounting the pump housing 30 and receiving electric control elements (not shown) for driving the pump 100 to operate.

The mounting base 10 includes a base body 12 and a retaining portion 14 disposed on the base body 12. The electric control elements are disposed in the base body 12. It should be understood that, in some other embodiments, the base body 12 may receive another element such as a heat dissipating element. The retaining portion 14 is disposed on one side of the base body 12, which includes two claws 141. The two claws 141 are disposed adjacent each other and spaced apart from each other. The two claws 141 are used to retain the pump housing 30. It should be understood that the number of the claws 141 is not limited to two, which may also be three, four or more.

In this embodiment, the pump housing 30 includes a cover 32, a main body 34, and an inlet pipe 36. In the illustrated specific embodiment, the cover 32 covers one side of the main body 34, and the inlet pipe 36 is disposed at the other side of the main body 34.

The cover 32 includes a mounting portion 321 and a cover portion 323 connected to the mounting portion 321. The mounting portion 321 is generally hollow cylindrical, which is mounted on the retaining portion 14 and located between the two claws 141. The mounting portion 321 is used to receive the driving mechanism 50. The cover portion 323 is disposed at one end of the mounting portion 321, for covering the main body 34.

The main body 34 is disposed on the cover portion 323, which includes a volute-shaped receiving portion 341 and a flow guide portion 343 connected to a circumferential side of the receiving portion 341. The receiving portion 341 defines a receiving chamber 3411 in communication with an inner chamber of the cover 32, for receiving the impeller 70. The flow guide portion 343 is generally hollow tubular and defines an outlet passage 3431 along the central axis thereof and communicating with the receiving chamber 3411, for allowing the fluid such as water, oil or gas to flow therethrough. The central axis of the flow guide portion 343 is substantially perpendicular to a central axis of the receiving portion 341.

The inlet pipe 36 is generally hollow tubular, which is disposed on one side of the receiving portion 341 away from the cover 32, with a central axis of the inlet pipe 36 substantially parallel to or coincident with the central axis of the receiving portion 341. A inlet passage 361 is defined in the inlet pipe 36 along the central axis thereof. The inlet passage 361 communicates with the receiving chamber 3411, which provides a passage for allowing the fluid such as water, oil or gas to flow therethrough.

Referring to FIG. 4, the main body 34 is volute shaped. The profile of the receiving chamber of the receiving portion 341 is a spiral line substantially formed by a plurality of arc segments approximated. In one embodiment, the plurality of arc segments includes 4 arc segments. A diameter of one of the arc segments, at which the starting point of the spiral is located, is denoted by Dl. A diameter of the outlet passage 3431 in the flow guide portion 343 progressively increases in a direction away from the receiving chamber 3411, such that a dynamic head of the fluid out of the receiving portion 341 is converted into a static head, thus ensuring smooth fluid delivery.

Further, the flow guide portion 343 and the receiving portion 341 are connected with smooth transition therebetween. An outlet flow area of the receiving portion 341, which is a cross-sectional area at the joint between the flow guide portion 343 and the receiving portion 341, is denoted by A1.

Referring again to FIG. 2 and FIG. 3, in this embodiment, the driving mechanism 50 is a rotary motor and, preferably, a single phase motor. The driving mechanism 50 is disposed in the mounting portion 321 of the cover 32, for driving the impeller 70 to rotate. Specifically, the driving mechanism 50 includes a driving body 52 and a driving shaft 54 disposed on the driving body 52, and the driving body 52 is fixedly disposed in the mounting portion 321. The driving shaft 54 is disposed at one end of the driving body 52 adjacent the main body 34 and extends from within the cover 32 into the receiving chamber 3411 of the main body 34. The driving shaft 54 can rotate, under the driving the driving body 52, to drive the impeller 70 to rotate.

In this embodiment, the driving mechanism 50 is a single phase brushless motor. The single phase brushless motor is capable of directed rotation, under the control of an electronic speed regulator, without additional backstop mechanism disposed in the pump 100, which improves the operating efficiency and stability of the pump 100.

Referring also to FIG. 5, the impeller 70 is mounted on the driving shaft 54 and received in the receiving chamber 3411. The impeller 70 includes an base plate 72, a shaft mounting portion 74, long blades 76, and short blades 78. In the illustrated specific embodiment, the shaft mounting portion 74 is disposed substantially at a center of the base plate 72, and the long blades 76 and the short disc 78 are disposed on the base plate 72.

Referring also to FIG. 6, the base plate 72 is substantially a circular disc, which is fixedly attached around the driving shaft 54 and is capable of rotation under the driving of the driving shaft 54. A diameter of the base plate 72, which is also a diameter of the base plate 70, is denoted by D2. A ratio of the diameter D1 of the first inner surface arc segment of the receiving portion 341 of the housing 34 to the diameter D2 of the base plate 72 (the diameter D2 of the impeller) is denoted by m, where m is equal to or greater than 1.05, and equal to or less than 1.1. That is,

m=D1:D2=1.05˜1.10

Balance holes 721 are formed in the base plate 72. In this embodiment, the balance holes 721 are through holes passing through the base plate 72, and the number of the balance holes 721 is three. The three balance holes 721 are arranged into a regular triangle which is centered at a center point of the base plate 72, and are spaced at uniform intervals on the base plate 72. In this embodiment, the balance holes 721 are round through holes. Centers of the three balance holes 721 are located on a same circle. A diameter of the circle on which the centers of the three balance holes 721 are located is denoted by D3. That is, the diameter at the locations of the three balance holes 721 is denoted by D3.

The balance holes 721 of the base plate 72 can balance the flow pressure on opposite sides of the base plate 72, maintain rotation stability of the impeller 70, and can thus reduce the operational vibration of the pump 100 and ensure the operation efficiency of the pump 100.

It should be understood that the shape of the balance holes 721 is not limited to the round-hole shape as described above. Rather, the balance holes 721 may also be designed to be holes of another shape, such as triangular holes, square holes, rectangular holes, or other polygonal holes, or any combination of the listed holes, as long as the three balance holes 721 pass through the base plate 72 and are uniformly distributed on the base plate 72 such that the flow pressures on opposite sides of the impeller are balanced so as to reduce the axial vibrations applied to the impeller 70 during rotation. It should also be understood that the number of the balance holes 721 is not limited to three; rather, it may be four, five, six or more.

Preferably, a ratio of the diameter D3 at the locations of the three balance holes 721 to the diameter D2 of the impeller 72 (impeller diameter D2) is greater than or equal to 0.36, and less than or equal to 0.9. That is, the ratio of the diameter D3 at the locations of the three balance holes 721 to the diameter D2 of the impeller 72 (impeller diameter D2) is:

D3:D2=0.36˜0.9

When the ratio of the diameter D3 at the locations of the three balance holes 721 to the diameter D2 of the impeller 72 (impeller diameter D2) is in the range of 0.36˜0.9, the axial force applied to the impeller 70 during rotation is relatively small, such that stable rotation of the impeller 70 can be achieved and the operation efficiency of the pump 100 can be ensured.

A cross section area of each balance hole 721 is denoted by S1. Preferably, S1 is greater than or equal to 9 mm2, and less than or equal to 240 mm2, i.e. S1=9˜240 mm2.

The shaft mounting portion 74 is substantially circular cylindrical, which is disposed substantially perpendicularly on one side of the impeller 72 opposite from the driving shaft 54 and is coaxial with the driving shaft 54. The shaft mounting portion 74 is located between the three balance holes 721. An end of the shaft mounting portion 74 is connected to base plate 72 with a smooth transition therebetween, for facilitating maintaining the rotation stability of the impeller 70.

There are a plurality of the long blades 76 disposed on the base plate 72 adjacent the shaft mounting portion 74 and surrounding the shaft mounting portion 74. In this embodiment, the number of the long blades 76 is three, and the three long blades 76 are uniformly distributed along a circumferential direction of the base plate 72. Each long blade 76 is an arcuate blade, and the three long blades 76 extend along radial directions of the base plate 72 to a radial rim of the base plate 72. In other words, each long blade 76 has a terminating end adjacent to the radial rim of the base plate 72 and a start end of each long blade 76 relatively closed to the shaft mounting portion 74 comparing to the terminating end of the long blade 76. A distance from the start end of each long blade 76 to an outer circumferential surface of the rotary shaft 74 is denoted by T1.

Preferably, a ratio of the distance T1 to the diameter D2 of the base plate 72 (that is impeller diameter D2) is ranged from 0.219˜0.4, i.e. T1/D2=0.219˜0.4.

When the ratio of T1:D2 is defined in such range, the width of the flow passage in the main body 34 is optimized, which makes the flow of the fluid in the main body 34 more stable and smooth and, at the same time, can prevent foreign matters from jamming the inlet of the impeller 70.

There are a plurality of the short blades 78 disposed on the base plate 72 adjacent the shaft mounting portion 74 and surrounding the shaft mounting portion 74. In this embodiment, the number of the short blades 78 is three, and the three short blades 78 are uniformly distributed along the circumferential direction of the base plate 72. Each short blade 78 is disposed between two adjacent long blades 76, i.e. each short blade 78 and each long blade 76 are alternatively arranged. Each short blade 78 is an arcuate blade, and the three short blades 78 extend along radial directions of the base plate 72 to a radial rim of the base plate 72. In other words, each short blade 78 has a terminating end adjacent to the radial rim of the base plate 72 and a start end of each short blade 78 relatively closed to the shaft mounting portion 74 comparing to the terminating end of the short blade 78. A distance from the start end of each short blade 78 to the start position of one adjacent long blade 76 is denoted by T2.

Preferably, a ratio of the distance T2 to the diameter D2 of the base plate 72 (base plate D2) is ranged from 0.219˜0.4, i.e. T2/D2=0.219˜0.4.

When the ratio of T2/D2=0.219˜0.4 is defined in such range, the width of the flow passage in the main body 34 is optimized, which makes the flow of the fluid in the main body 34 more stable and smooth and, at the same time, can prevent foreign matters from jamming the inlet of the impeller 70.

In this embodiment, the plurality of the long blades 76 are disposed on the base plate 72 and are spaced from each other at uniform intervals, the plurality of the short blades 78 are disposed on the base plate 72 and are spaced from each other at uniform intervals. The distance T2 between the start end of each short blade 78 and the start end of one of two long blades 76 neighboring the short blade 78 may be equal or unequal to the distance T2 between the start end of the short blade 78 and the start end of the other one long blade 76 neighboring the short blade 78. It is more helpful for stabilizing the flow when the distances T2 are all equal.

Referring to FIG. 6, a blade outlet flow passage is cooperatively bounded by a distal end of each long blade 76, a distal end of each short blade 78, and the edge of the base plate 72. A blade outlet flow area is denoted by A2 (indicated by the broken line of FIG. 6). The three long blades 76 and the three short blades 78 form six blade outlet flow passages on the base plate 72, and a total area of the six blade outlet flow passages is referred as an impeller outlet flow area denoted by A3 (not labeled). A ratio of A1 to A3 is denoted by k. In this embodiment, k is greater than or equal to 0.2, and less than or equal to 0.5. That is, the ratio of A1 to A3 satisfies:

k=A1:A3=0.2˜0.5

When the ratio of the outlet flow area A1 of the receiving portion 341 of pump housing 30 to the impeller outlet flow area A3 is in the range of 0.2˜0.5, the pump housing 30 provides therein the flow passage with sufficient width for flowing of the fluid. In addition, this increases the velocity of the fluid and hence enhances the efficiency of the pump 100 while ensuring a compact size of the pump 100.

Referring also to FIG. 7, further, the long blades 76 and the short blades 78 have substantially the same height along an axial direction of the base plate 72. When the impeller 70 is received in the receiving chamber 3411, top ends of the long blades 76 and/or the short blades 78 are spaced from a bottom wall of the receiving chamber 3411 by a predetermined gap. That is, the predetermined gap is formed between the impeller 70 and the bottom wall of the receiving portion 341. The predetermined gap is referred to as an impeller gap denoted by T3.

A ratio of the impeller gap T3 to the diameter D2 of the base plate 72 (impeller diameter D2) is denoted by G. Preferably, G is greater than or equal to 0.04, and less than or equal to 0.12. That is, the ratio of the impeller gap T3 to the diameter D2 of the base plate 72 is:

G=T3:D2=0.04˜0.12

When the ratio of the impeller gap T3 to the diameter D2 of the base plate 72 (impeller diameter D2) is in the range of 0.04˜0.12, the receiving chamber 3411 provides therein the determined flow passage for flowing of the fluid. In addition, this increases the velocity of the fluid and hence enhances the efficiency of the pump 100 while ensuring a compact size of the pump 100.

In assembly of the pump 100 of this embodiment, the impeller 70 is first mounted to the driving shaft 54 of the driving mechanism 50, and the driving body 52 of the driving mechanism 50 is received and fixed in the mounting portion 321 of the cover 32. The cover 32 is then placed to cover on the receiving chamber 3411 of the housing 34, with the impeller 70 received in the receiving chamber 3411. Finally, the assembled pump housing 30 is mounted to the mounting base 10. In use of the pump 100 of this embodiment, the pump housing 30 is first filled with a fluid such as water, oil or gas, the inlet pipe 36 is fluidly connected with a container receiving the fluid, and the flow guide portion 343 is fluidly connected to the outside environment or another container for receiving the fluid. The driving mechanism 50 is then driven to rotate, which in turn drives the impeller 70 to rotate in the pump housing 30. Under the action of the centrifugal force and a pressure difference established between the blades of the impeller 70 and the inner surface of the pump housing 30, the fluid continuously flows from the container and the inlet pipe into the pump housing 30, and is delivered to the outside environment or the another container for receiving the fluid via the flow guide portion 343.

In the pump 100 of the present invention, the impeller 70 includes the alternatively arranged long and short arcuate blades, which further optimizes the design of the flow passage in the pump housing, thereby resulting in more smooth and stable flow of the fluid and enhanced fluid delivery efficiency. In addition, the extending direction of the blades of the impeller 70 is in compliance with the rotation direction of the impeller 70, which reduces the occurrence of unstable phenomenon in the flow passage such as flow separation and secondary flow and hence improves the overall performance of the centrifugal pump. Moreover, the pump 100 uses the single phase motor as the driving mechanism for driving the impeller 70 to rotate, which makes it easier to start the pump at low voltage.

Although the invention is described with reference to one or more embodiments, the above description of the embodiments is used only to enable people skilled in the art to practice or use the invention. It should be appreciated by those skilled in the art that various modifications are possible without departing from the spirit or scope of the present invention. The embodiments illustrated herein should not be interpreted as limits to the present invention, and the scope of the invention is to be determined by reference to the claims that follow.

Although the invention is described with reference to one or more embodiments, the above description of the embodiments is used only to enable people skilled in the art to practice or use the invention. It should be appreciated by those skilled in the art that various modifications are possible without departing from the spirit or scope of the present invention. The embodiments illustrated herein should not be interpreted as limits to the present invention, and the scope of the invention is to be determined by reference to the claims that follow. 

1. An impeller comprising: an base plate; a shaft mounting portion disposed on the base plate, a plurality of long blades and a plurality of short blades disposed on a side of the base plate, the plurality of long blades and the plurality of short blades being alternatively arranged on the base plate along a circumferential direction of the base plate, and surrounding the shaft mounting portion, the long blades and the short blades being all arcuate blades.
 2. The impeller of claim 1, wherein the shaft mounting portion is a circular cylinder protruding from the base plate.
 3. The impeller of claim 1, wherein each the long blade extend along radial directions of the base plate, each long blade has a terminating end adjacent to the radial rim of the base plate and a start end of each long blade relatively closed to the shaft mounting portion comparing to the terminating end of the long blade, a ratio of a distance between a start end of each long blade and an outer circumferential surface of the shaft mounting portion, to a diameter of the base plate is greater than or equal to 0.219, and less than or equal to 0.4, and/or, a ratio of a distance between a start position of each of the short blades and the start position of one adjacent long blade, to the diameter of the base plate is greater than or equal to 0.219, and less than or equal to 0.4.
 4. The impeller of claim 3, wherein the long blades are spaced from each other at uniform intervals, the short blades are spaced from each other at uniform intervals, and distances between a start end of each short blade and start ends of two long blades neighboring the short blade are the same.
 5. The impeller of any of claims 1, wherein the base plate defines a plurality of balance holes in the base plate.
 6. The impeller of claim 5, wherein the balance holes uniformly distributed on the base plate.
 7. The impeller of claim 6, wherein centers of the balance holes are located on a same circle, and a ratio of a diameter of the circle to a diameter of the base plate is greater than or equal to 0.36, and less than or equal to 0.9; and/or, a cross section area of each balance hole is greater than or equal to 9 mm², and less than or equal to 240 mm²; and/or, each balance hole has at least one of the following shapes: round, square, triangle, and rectangle.
 8. The impeller of any of claims 1, wherein the shaft mounting portion is connected to the base plate with a smooth transition therebetween.
 9. A pump comprising: a driving mechanism; and an impeller connected to the driving mechanism, the driving mechanism being configured to drive the impeller to rotate, the impeller comprising: an base plate; a shaft mounting portion disposed on the base plate; and a plurality of long blades and a plurality of short blades disposed on the base plate, the plurality of long blades and the plurality of short blades being alternatively arranged on the base plate along a circumferential direction of the base plate, and surrounding the shaft mounting portion, the long blades and the short blades being all arcuate blades.
 10. The pump of claim 9, wherein the pump further includes a pump housing, the pump housing includes a main body and a cover disposed on the main body, the main body includes a volute-shaped receiving portion and a flow guide portion (343) connected to the receiving portion, the driving mechanism is mounted to the cover, and the receiving portion defines a receiving chamber accommodating the impeller.
 11. The pump of claim 10, wherein the profile of the receiving chamber of the receiving portion is a spiral line substantially formed by a plurality of arc segments approximated, a ratio of a diameter D1 to a diameter D2 is greater than or equal to 1.05, and less than or equal to 1.1, wherein D1 is a diameter of one of the arc segments, at which the starting point of the spiral line is located, D2 is a diameter of the base plate; and/or, a ratio of an outlet flow area of the receiving portion to an outlet flow area of the impeller is greater than or equal to 0.2, and less than or equal to 0.5; and/or, a ratio of a distance between the impeller and a bottom wall of the receiving portion of the main body to the diameter of the base plate is greater than or equal to 0.04, and less than or equal to 0.12.
 12. The pump of claim 10, wherein the flow guide portion defines an outlet passage communicating with the receiving chamber of the receiving portion, and a diameter of the outlet passage increases progressively in a direction away from the receiving portion; and/or, the pump housing further includes an inlet pipe, the inlet pipe is disposed at one side of the receiving portion opposite from the cover, and an inner chamber of the inlet pipe is in communication with the receiving chamber of the receiving portion.
 13. The pump of claim 10, wherein the cover includes a mounting portion and a cover portion disposed on the mounting portion, the cover portion covers on the main body, and the driving mechanism is mounted in the mounting portion.
 14. The pump of claim 13, wherein the pump further comprises a mounting base, and the mounting portion of the cover is fixedly disposed on the mounting base.
 15. The pump of claim 14, wherein the mounting base includes a base body and a retaining portion disposed on the base body, the retaining portion includes two opposed claws, and the mounting portion is retained between the two claws.
 16. The pump of claim 10, wherein the driving mechanism is a single phase motor.
 17. A fluid delivery device comprising: a driving mechanism; and an impeller connected to the driving mechanism, the driving mechanism being configured to drive the impeller to rotate, the impeller comprising: an base plate; a shaft mounting portion disposed on the base plate; and a plurality of long blades and a plurality of short blades disposed on the base plate, the plurality of long blades and the plurality of short blades being alternatively arranged on the base plate and surrounding the shaft mounting portion, the long blades and the short blades being all arcuate blades. 